The present invention relates to the fields of radiology and nuclear medicine, and in particular to the use of rectilinear scanners for the performing of a number of diagnostic studies of bodily tissue and organs.
The fields of radiology and nuclear medicine have long been concerned with the development of techniques for the non-invasive diagnosis of medical conditions of human or animal tissue. Generally procedures involve the use of x-ray radiation that is passed through a body to provide static or dynamic transmission studies, or alternatively, the use of radiopharmaceuticals that are introduced into the patient such that their distribution or concentration can be viewed by the detection of the resulting gamma ray emissions of variable intensity.
Initially these systems used an analog rectilinear scanner to generate static images wherein a scintillation-type gamma ray detector equipped with a focusing collimator was moved continuously, through a series of parallel sweeps, to scan the region under study.
Rectilinear scanners have more recently been used with a dual energy radioactive source for conducting transmission bone densitometry studies. Early analog devices have been used for conducting emission studies with an injected isotope as referenced above. In either case rectilinear scanners have seen very limited use due to the development of so-called "gamma camera" systems developed in the last decade.
Because of the interest in performing dynamic studies such as myocardial perfusion, wall motion, lung perfusion and lung ventilation, systems were developed to view the entire region of interest. These "gamma camera" systems utilized a large diameter sodium iodide crystal in conjunction with a matrix of photomultiplier tubes and a multi-channel collimator to perform a large variety of emission studies. The problem with gamma cameras using scintillation detector crystals is that the resolution is limited by both the light coupler between the detector and the photomultiplier and, more importantly, by the scattering of the radiation emitted from the in vivo region of investigation. Even if the resolution of gamma cameras were adequate they do not produce an image of the tissue of actual size. Gamma camera systems are also extremely expensive, require a large space to be used, and necessitate a relatively high level of operator training. In addition, the use of gamma cameras for performing static studies has tended to lower their cost effectiveness due to there use on these low revenue static studies.
As a result of these factors, there is a need for a relatively inexpensive, portable and easy to use rectilinear scanner that can be used for diagnostic applications requiring the generation of static images. This will operate to free the gamma camera systems for performing the high revenue dynamic studies for which they are intended.